1. Field of the Invention
Various type of electrochemical measuring electrodes are at one end provided with a gas permeable membrane which is retained in position by means of an elastic or resilient ring surrounding said end of the measuring electrode. As the user of such measuring electrodes has to mount and/or replace the membranes on the measuring electrodes from time to time it is important that the membranes may be mounted in a manner which is not only simple, but also secures a correct and reproduceable mounting.
The present invention relates to a mounting device for mounting a membrane or foil in a stretched condition at one end of a measuring electrode member or a similar rod-shaped or tubular member.
2. Description of the Prior Art
Austrian Patent Specification No. 284,328 discloses a device or tool for mounting membranes on measuring electrodes. This known tool comprises a body member or base member having a throughgoing passage defining an upwardly facing shoulder. When a membrane has to be mounted by means of a resilient or elastic ring the user must first place the ring on a cylindrical mandrel having a conical tip. The user places the ring around the conical tip and moves it manually onto the cylindrical part of the mandrel, whereby the ring is being resiliently stretched. Thereafter, the user inserts the mandrel on which the ring is placed into the passage formed in the base member or body member till the ring abuts the upwardly directed shoulder therein. The user now has to place a membrane on the upper side of the base member and thereafter a heavy retaining ring on the upper side of the membrane whereby the rim portion of the membrane is being clamped between the upper side of the base member and the lower side of the retaining ring. When the mounting tool has been made ready as described the user inserts the end portion of an electrode on which the membrane should be mounted, in the retaining ring and pushes the electrode towards the membrane which will thereby be wrapped around the electrode end portion, the rim portion of the membrane being pulled out from its position between the retaining ring and the base member. During the continued downward movement of the electrode end portion through the passage in the base member, the electrode end portion with the membrane wrapped therearound engages with the upper free end of the cylindrical part of the mandrel and pushes the mandrel downwardly in the tool passage. Thereby the stretched resilient ring abutting the upwardly directed shoulder will be slipped off the mandrel and moved to a position around the electrode end portion having an outer diameter equal to or somewhat smaller than the outer diameter of the cylindrical part of the mandrel.
Even though use of the known tool described above somewhat facilitates the mounting operation compared with mounting procedures previously used, it would be desirable to make the membrane mounting procedure still more simple for the user and thereby further to reduce the risk of erroneous mounting.